Bowel and urinary bladder dysfunction in spinal cord injury patients accounts for severe morbidity and mortality. Improvements in medical and surgical management of fecal impaction and urinary sepsis have resulted in greater life expectancy. Nevertheless, the duration of time and effort spent in these activities, often with caregivers' assistance, frequently precludes useful social activity at home or in the workplace. Partial control of both these functions has been achieved recently employing a surgically implantable sacral anterior nerve root stimulator (The Finetech-Brindley device). Aims 1. To measure the efficacy of the Brindley device in achieving bowel and bladder evacuation, with and without posterior rhizotomy. 2. To advance the capability of this neuroprosthetic technique using selective forms of neural stimulation which enable activation of small nerve fibers to occur while blocking transmission in larger nerves. This approach may permit electrical stimulation of bladder and bowel to occur, via small fibers, with little or no contraction of their sphincters. 3. To test anew type of electrode with blocking capability in human subjects. This electrode may permit the use of lower currents for selective activation and have a lower risk of mechanical damage to nerves. Methods 1. Twenty subjects with spinal cord injury will be studied by clinical and laboratory investigation before and after implantation of the Brindley stimulator. Urological studies will assess bladder emptying, infection, urodynamic parameters and vesico-uretic reflux. Colo-rectal studies will assess effectiveness of defecation, colonic and anorectal motility. The possible danger of electrical stimulation causing autonomic dysreflexia will be assessed. 2. Use of more selective electrical stimulation will be tested by using a computer-controlled transmitter capable of more accurate, flexible and reproducible stimulation and of generating stimuli designed to produce selective activation of the bladder or rectum without contraction of the external urethral or anal sphincters. 3. New electrodes designed to produce selective activation at low currents will be tested pre-operatively during the implantation of the Brindley stimulator, and compared with the electrodes at present in use to stimulate bowel and bladder. The achievement of these aims will have significant impact on bladder and bowel control in spinal cord injury patients and improve their health and ability to participate in education, employment and social life.